Fix main handling in dart2js and add tests.

dart/tests/language/main_test.dart

Index: dart/tests/language/main_test.dart
diff --git a/dart/tests/language/main_test.dart b/dart/tests/language/main_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..719ba81e2a63130242d62f54177418df6962e1bd
--- /dev/null
+++ b/dart/tests/language/main_test.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+main(
+
+a         /// 01: ok
+a, b      /// 02: ok
+a, b, c   /// 03: static type warning, runtime error
+a, b, {c} /// 04: ok
+a, b, [c] /// 05: ok
+
+[a]       /// 20: ok
+a, [b]    /// 21: ok
+[a, b]    /// 22: ok
+
+{a}       /// 41: ok
+a, {b}    /// 42: ok
+{a, b}    /// 43: ok
+[a, b, c] /// 44: ok
+{a, b, c} /// 45: ok
+
+) {
+}